TA21 Clutch Judder

Hi. Can anyone advice on the most likely cause of  Judder on take off from Stationery. Not desperate but worrying as to whether it will get worse. Clutch was replaced about 5 years ago. Posted by JSR 25/10/2013 10:35:55

Could be knackered engine/gearbox mounts,easy to check with a crow bar,oil on the clutch plate,worn cushion springs on the plate,uneven wear and hence  release by the thrust ring, worn cover plate causing uneven take up. Needless to say these  last items need the gearbox out if you only replaced the plate 5 years ago the cover plate/thrust ring are most likely the problem,probabley. Good luck Posted by Peter Martin 30/10/2013 10:36:07

Peter really covered it all. I experienced the same problem. That said check to see if the near side engine mount has a heat shield protecting it. In my case the constant exhaust heat exposure had helped destroy the rubber mount. By carefully jacking up the motor or use of a crow bar the split in the rubber became obvious. I have the old angled mount and when under pressure it was impossible to tell that it had split. If you have to remove the mount it may be difficult to relocate the bolts. To that end making a spare tapered bolt  will allow you to tap it into place and align the other hole. A bolt can them be placed and loosly fastened. The tapered bolt can then be removed and replaced with the correct fastener.  If a heat shield is missing it is not difficult to fabricate a new one and use the bolts as the anchor points. Posted by RichardWallach 07/11/2013 07:17:58

I have seen  a picture (of a car for sale on the web) of a TA21 that had a steady bar, going sideways from the gearbox to the chassis. My own car (1953 TC21) doesn't have this, just rubber engine and gearbox mounts, and the pair of longitudinal rods going forwards from the bellhousing to the front of the chassis. Is the sideways bar an addition made by the factory? I haven't driven my car yet (a long, slow restoration) so can't really comment further. Posted by drdowhitt 07/11/2013 11:17:17

Some cars had the clutch symptoms as discussed and either The Works or Red Triangle (I am not sure which) devised a kit containing some rods that attached from the box to the chassis (if my memory serves me correctly). RT has in the past held some stock of these. That said if your car was symptomatic of this at the outset it would have probably been fitted with this kit as the other problems already mentioned would have been eliminated. With that in mind I tend to think that likely cause of the symptoms are a possible combination of the ones already listed above. Posted by RichardWallach 09/11/2013 06:17:58

Another thought .The fiendish mechanical system of springs, push rods,pull rods , turn-buckles (yes),fulcrum pins,bushes etc that transfer the downward movement of the clutch pedal to the horizontal operation of the arm on the gearbox does not really lend itself to smooth take up. Might be worth checking it for play/backlash and general freedom of movement/lubrication before tearing the gearbox out. Posted by Peter Martin 09/11/2013 09:27:58

In adding to Peter's last comment also check the engine stabiliser rods to see if they are just in tension. The tension on both needs to be the same. These rods actually prevent the engine from moving rearwards when the clutch is depressed. Hydraulic clutch systems do not use the chassis as the fixed point hence there is no movement of the engine/gearbox when the clutch is depressed and therefore &quot;stay&quot; rods are not needed.  It would be worthwhile to rebuild the stay rods as some stage. There is a rubber bushing (can't be seen) at the engine end. This bushing is sandwiched between two sleeves and is very difficult to ascertain its condition in situ. Remember these are probably up to 60 years old by now. Replacement units are no longer available from Red Triangle. That said I located a similar sized bush from the suspension section of  Scott’s Old Rubber catalogue, see <!-- m --><a class="postlink" href="http://www.scottsoldautorubber.com.au/products111.jpg">http://www.scottsoldautorubber.com.au/products111.jpg</a><!-- m --> . All that has to be done is to cut off the “top hat” section of the new bush. That done all measurements are near enough to the Alvis bush and what’s more the bush is made of rubber as is the original. To remove the old bushes that were firmly &quot;glued&quot; into place, I used an electric drill and basically cut them out. I then cleaned both metal surfaces and with the aid of some rubber grease fitted the new bush.   I found that tensioning at the gear box to be very fiddly and to get around this I actually made two adjusters, as used to adjust the clutch, by using old clutch rods. It was a simple task to use a spanner to adjust each rod just to be in tension and then to lock it with the locknut.   I have had absolutely no clutch shudder problems since.  I hope all this helps. Posted by RichardWallach 09/11/2013 22:27:31